1. Field of the Invention
The present invention relates to a radio apparatus and a radio network system including the same. Specifically, the present invention relates to a radio apparatus capable of autonomously estimating a position and a radio network system including the same.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.08
Wide spread use of car navigation systems using GPS (Global Positioning System) and the start of personal navigation system using portable telephones in these days have lead to rapid development of services based on position information (LBS: Location Based Service) in mobile market.
By way of example, various services related to crime-prevention utilizing position information of a person, a car or a pet have been provided. Further, mobile communication providers started providing services of transmitting/receiving current position information by e-mail with map information.
It is expected that various and many other LBSs will be introduced to the market, and so-called location business will surely thrive.
For market expansion, however, it is essential that the scope of use covers not only outdoors and facilities located outdoors but also indoors and facilities/equipment indoors, and that not only the position of an object but also dynamic state of the object can be handled.
On the other hand, cost-effectiveness of micro devices and diffusion of radio communication technique have lead to reduction in size and cost and higher performance of radio digital devices (RFID tag, Bluetooth (registered trademark) and ZigBee (registered trademark)) allowing short-distance communication with small power, whereby such devices are now available for various purposes.
Because of the characteristics of radio digital devices as such, these devices are expected to be attached to various and many daily-use articles of everyday life, and be distributed on a massive scale. When radio digital devices are attached to general articles of everyday life, an environment becomes a reality in which various articles that could not have been the object of information processing in the past and wide areas in which these articles exist become the object of information processing. In other words, a ubiquitous computing environment is being built.
In the ubiquitous computing environment, human-oriented information processing is desired. Therefore, a number of studies and experiments have been made, which are related to LBS for offering services based on positional relation of a human being and ubiquitous articles and their states. Such studies and experiments of LBS include highly sophisticated LBS in which positions and states of a human being and articles are detected accurately and more delicate and real-time services are provided, utilizing a free space fully equipped with sensors (A. Harter, A. Hopper, P. Steggles, A. Ward, and P. Webster, “The Anatomy of a Contextaware Application”, MOBICOM 1999, (1999)).